Portable quench oil tester



H. W. HUSA PORTABLE QUENCH OIL TESTER 5 Sheets-Sheetv l Jan. 17, 1956Filed NOV. 30, 1955 rill ||||||||l||| Ill...

Jan. 17, 1956 H. w. HUSA 2,736,894

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United States Patent 2,730,894 PORTABLE QUENCH OIL TESTER ApplicationNovember 30, 1953, Serial No. 395,208 8 Claims. (CI. 73-53) Thisinvention relates to an apparatus for evaluating the quenching power ofquenchingfluids.

Heretofore, the evaluation of the quenching power of fluids has involvedtests wherein a steel specimen is heated to austenitizing temperature,quenched in a fluid, machined and then either etched or hardnessreadings taken, or both. Such methods are tedious, expensive and requireexpert interpretation. Furthermore, the apparatus is expensive and isnot portable in the ready sense of the word. Likewise, such tests failto give a temperature-time record of an object cooling in the fluid.

Accordingly, it is an important object of this invention to provide aquench oil tester which is accurate, inexpensive and portable. A furtherobject is to provide an apparatus which gives indications of the valueof a quenching fluid that can be readily interpreted by a lay audienceand can be demonstrated before large as well as small groups. Anadditional object is to provide a demonstration method and apparatuswhich is simple, reproducible and rapid. p

The need for a device which would evaluate the quench ing power of afluid with a minimum of effort and in a minimum time has been felt forsome time. To. make such an evaluation, it is desirable to produce arecord of the fluids ability to cool at a particular temperature(instantaneous cooling rate) and to obtain a visual record which may becompared with the record of a reference quenching oil so as to giveanindex of the oils quenching power and of its desirability fordifferent types of quenching work. Such evaluation work enables one tomake recommendations with regard to the compounding of quenching oils,to make routineproduct control,

tests, and to evaluate operational difliculties Where quenching oils arein actual use. It is accordingly an object of my invention to obtain avisual indication for a fluid under test which may be readily andquickly compared with a record of a reference quench oil.

It is a further object of my invention to provide a system which willevaluate aquenching oil in an economical, convincing, convenient andspectacular manner without requiring any substantial skill in theoperation.

If a thermocouple bead were placed in a steel specimen, the thermocouplewould measure the temperature of the specimen mass and would be affectedby the chemical make-up of the specimen. For example, a steel specimencooling from the austenite range transforms to pearlite or tomartensite, depending upon its chemical composition and its rate ofcooling. Chemical heat is released in this phase transformation and,accordingly, a thermocouple in the metallic mass would be influenced bythe phase change to give. anerroneous indication of the coolingphenomenon transpiring at the specimen surface. To add to the confusion,the heat liberated depends upon the completeness of the transformationwhich is different for different starting temperatures and different fordifferent cooling rates. This is a serious limitation in view of thefact that the majority of, thecorn mercial Work is done at temperaturesin a range of 25 to 50 F. above the transformation temperature. Itis,therefore, an important object of my invention to provide a system whichdoes not require the heating and cooling of a substantial mass of metal.

A further object is to provide an apparatus which is compact, portable,and adaptable for testing quenching oil in the field. The foregoing andadditional objects of my invention will become apparent to those skilledin the art asthe description thereof proceeds.

Briefly, my portable fluid quenching tester embodies a movablethermocouple means, the head of which is heated in a furnace to thequench temperature, i. e., the temperature from which the specimen is tobe quenched. When a sliding support for the thermocouple is released,the heated bead is immersed in a body of quenching fluid and a switchmeans is tripped by the movement of the thermocouple holder.

Only a very small amount of fluid is necessary for The thermocouple beadis suspendedwithin the furnace by means of the sliding holder which maybe an inverted U-shaped support. The arms of the inverted U areconstrained to travel in a substantially vertical path. -When the beadof the thermocouple is at the selected quenching temperature within thefurnace, the sliding support is released thereby permitting the supportand thermocouple means to slide as a unit under the influence ofgravity. This action removes the thermocouple bead from the furnace andimmerses it inthe fluid sample. When this occurs, the first switch isclosed and the timer begins to operate. A current indicator meansindicates the temperature of the thermocouple bead and a second switchresponsive to the current indi cator is closed by the movement of theindicator needle down-scale. The complete operation of this apparatusmay, therefore, be summarized as follows.

A release for the sliding holder is operated manually and has twopositions. .In its first position, it holds the slide aloft andpositions the thermocouple bead within the furnace for heating. In itssecond position, the release is pulled away from the frame thuspermitting the sliding holder to drop and to carry with it thethermocouple bead from the furnace into the test fluid disposed below.The sliding holder closes the first switch which starts the timer. Thethermocouple bead is cooled by the oil bath and its temperaturedecreases. At a preselected lower temperature level, contacts of thesecond switch areclosed and the timer is automatically stopped. Theapparatus has thereby accurately measured the time required for thethermocouple bead to cool from a selected temperature to some designatedlower temperature.

Further details of my invention will be described in connection with theaccompanying drawings wherein:

Figure ,l is a schematic view of the wiring diagram;

,Figure 2 is a perspective, partly in section, of one embodiment of theapparatus incorporating features of my invention; and

couple 10 is supported by the thermocouple connector which is supportedby thc guillotinc slide 16. The thermocouple 10 is heated to quenchingtemperature in the electric furnace 11 which is preferably cylindrical,open at bothcndsand.mountedso that itsaxis is substantially vertical.

When the desired {temperatureof the thermocouple .10 is indicated on theindicator '13, the position of switch 17 istchanged (to ,derener-gizethctfurnacewindings 11a and makepowenavailable-qto .tbe measuringcircuit)and the thermocouple .10; is mechanically released by the sliderc1eas'e.18 to fall throughthe furnace lt-Linto'the quenching fluid 19withinthesample container 12. When the thermocoupl e 10 enters-thefiuid.19 incontainer 12, the guillotine. slide 16 trips the nicro switch 21to energize an electric timer ,14 ,and ,D. C. ,power supply 25.

llncooling from theinitial guenching temperature, the thermocoupletemperature indicator hand '20 travels downgscale toclose thelow limitswitch 27 having one contact thereofcarried ,hy the indicatorhand 20.This a switch 27 is built-into the-indicator means '13 and maybetmanually set tO-gClOSC at any desired temperature. The closing of.the {switch '27 energizes :relay v24 .(via leads 2,2:and23 and-D.C.;powe r sourceZS) which-stops electric timer 14 .by opening relaycontacts .2411. .In this mann er,::the cooling time from .any :desirediinitial temperature-to :any desired final temperature .rnay beaccurately measured. The lengthtof :the ifreefallpath of thethermocouple 1.0;and the;timc;spent;.in free fall are not critical solong as the thermocouple bead 10a has not dropped below the temperaturefrom which :quenching is to in tiatelbythe time itreachesithezfluidsurface.

The thermocouple 10 and the'slide 16-move;in;aguillotine frame .26 orsome other :mcchanim'l slide device which holds'gthe thcrmocouple .10in-the furnace 11 .dur-

ing the -heating :ofthe thermocouple 10 and yet permits it to dropthrough the heater .11 to .a fiuid both 19 when released.

The furnace .11 may be .a light weight, rapid heating, electric furnace.,Itis preferably not va continuous duty furnaccpbut one that is turnedvon :and off for each quenchingtest. The thermocouple Ill-is brought upto temperature in less than one minute .after the initial test (whichrequires about three .minutes of heat-up time). V

The use of asbarethermocouplc of the furnace type assuresthe operatorthat :the temperature-time phenomenon is characteristic of theoil under.test.

extended periods of-time. Yet, the temperature should 1 be :high enoughto :be the :austenitizing range for most steels. A typicaltemperaturaand one :that can becorrelated with industrial quenchingwork, is l600 A brief description of the processof quenching steel fromthe metallurgical yiewpoint is in order to clarify the quenchingfluid-characteristics required. The steel is first heated to such avtemperaturethat austenite, a solid solution .of carbon in gamma iron,is formed from the original steel constituents. When the austeniteiscooled, several possible final products can result depending on therate of cooling employed (actually depending on time .in :thetemperature range in which the transformation takes place). Slow coolingproduces pearlite, a relatively soft constituent. Afaster rateof coolingcan lead, in .certainlow alloy steels, :to a structure called bainite, asomewhat harder constituent. When the rate of cooling -.is suflicientlyrapid, the pearlitekand bainite transformations can both be avoided anda new structure called martensite,-the hardest and most brittleconstituout, is formed. In the usual quenching process it is desired toachieve the -martensi te structure so that a closer control can bemaintained on the properties of 4 r V the steel during the subsequenttempering or heating stages.

The large temperature gradients produced in the steel during rapidcooling lead to large thermal stresses. An additional'stress is createdby the formation of martensite from austenite, since this transformationresults in an increase in volume. Thusthe magnitude of the temperaturegradient .and therate ofiormation of -martensite must be controlled toprevent the so-called quench Table I Temperature tor-Most .RapitlFormation F. Transformation .oi-A-ustenite to- Isothermal 'lrans- DuringQuenching I formation (Approx) (Approx) Pear-lite; 950 to 1,150.500150900 Bainite in steels .750 to 900 600110 750 during cooling.

l l I Does not form except 1 l I It is now possible to define thecooling characteristics desired inan oil-base type quenchingifiuid foruse with theoiI-hardening grades of steel .(as opposed to waterhardeningandair-hardening. grades). This fluid should have .the highestattainable cooling rates in the temperature .range 1600 .to 500 Fraudshould revert .to slow coolingb'elow about 500 F.

For a givenpart made of a given steel the hardness at any .point isdetermined by the time-temperature history of the point duringquenching. However, the quenching fluid can only :afiect conditions atthe metal Surface. This makes possiblethe evaluation .ofquenching oilsby. determining the time-temperature relationship in the quenching :of asmall mass having a high surface to volume ratio. The magnitude of thetime interval required for the thermocouple bead tocool from. 1600 F. to.500 F..:is,.there for.e, a sound indexof the quench ing ability of thequenching .fluid. v 4 'Other time indexes may. be obtained by'quenchingfrom a difierent initial temperature to the same or a different finaltemperature. This'is a particularly advantageous arrangement when thequenching oil is -.to be tailored to fita specific steel. Completeinformation can be obtained on any fluidbya series of quenches from aparticular quench temperature to several end temperatures. For example,the-data .inTable II below were obtained on a straight run quenchingoil, a superfast quenching-oil, and water.

double-throw switch 17 shown in the off position is manually operated toapply power to the heater windings 11a of the furnace 11. The bead a ofthe thermocouple 10 rises in temperature and the thermo-voltagc thusgenerated by the thermocouple 10 is fed to coil 28 of the indicator 13and the indicator needle is deflected. When the indicator 13 indicates1600 F., the switch 17 is thrown to disconnect the furnace heaterwindings 11a and make power available to the measuring circuit. Theswitch 17 is a safety device which prevents application of power to boththe heater 11 and the meas' uring circuit leads 29 at the same time.This prolongs the heater life by disconnecting the heater 11 when it isnot needed for heating the thermocouple 10.

In Figure 2, theguillotine slide 16 is released by moving the sliderelease 18 to the dotted position. In falling past the microswitch 21,the guillotine slide 16 closes the switch 21 to start the micro-timer 14and energize D. C. power supply 25. The container 12 is positioned belowthe opening in furnace 11 and on the base 26a of the frame 26. The base,being provided with a guide ring 31, assures the container of beingproperly positioned to receive the falling thermocouple 10.

The thermocouple bead 10a is cooled by the oil bath 19 in container 12and the thermo-voltage output of the thermocouple 10 decreases therebycausing the indicating needle 21) to travel down-scaleuntil the secondmicroswitch 27 is closed. The current supplied by the D. C.

source 25 flows through the contact locking coil 30,

through the contacts of the second micro-switch 27 and through the relay24. When the contacts of switch27 touch, small current begins to flowwich assists the thermocouple voltage in building up contact pressure.This reduces contact resistance and results in rapid closing of thecontacts. The closing of switch 27 energizes the relay 24 and thecontacts 24a of relay 24 open and deenergize the micro-timer 14. Thetime interval indicated on the face of timer 14 is an index of thequenching ability over the range of temperatures covered.

The quench test thus being completed, the thermocouple lll is removedfrom the support frame 26 and the bead 10a washed in a suitable solvent,such as carbon tetrachloride. This prevents smoking of the thermocouple10 in the heater 11 on the next test cycle.

In Figures 3 and 4, the relative arrangement of the guillotine slidemeans 16, the thermocouple means 10, the furnace means 11 and the timercontrol means 21 have been illustrated. Figure 3 illustrates the initialposition, i. e., the heating of the thermocouple bead 10a in the furnace11, whereas Figure 4 illustrates the closing of micro-switch 21 duringthe time that the thermocouple bead ltla enters and is within the bath19.

Since the guillotine slide 16 has considerable weight and is freefalling, the shock absorber 32 may be provided to stop the fall thereof.This is shown in Figure 2 wherein the guillotine slide 16 is verticallymovable within slide guide rails 33 which are fixed to the plates 34 and35 of the instrument frame or housing 26. The guillotine slide release18 is pivoted at 36 to the cross-member 37 and has a catch 38 whichsupports the cross-arm 39 of the slide 16 when it is desired to hold thethermocouple bead 10a within the furnace 11. The thermocouple 10 issupported at one end by the connector 15 which comprises the coldjunction and is secured within the cross-head 4'0 of the slidingguillotine holder 16. Leads 41 and 42 join the connector 15 to pyrometercoil 28. The furnace 11 is supported by the back wall of the housing 26so that the cylindrical interior is insubstantial vertical alignmentwith the guide rails 33 which accommodate the legs of the invertedU-shaped slide 16.

Any tendency of the slide 16 to vibrate before it comes to rest on theshock absorber 32 supported by the stop bar 32a can be minimized by thecurved leaf spring brakes 44. These brakes are fixed to the back wall ofthe housing 26 and have a curved contacting surface which holds theslide 16 in its rest position.

All of the components of the device can be carried by one man in acombination carrying and display case (not shown) and the instrumentwith its display timer can be set up on a table or bench for theevaluation of samples in the bottle or jar containers 12.

Although I have described my invention with reference to a particularembodiment thereof which has been set forth in considerable detail, itshould be understood that this is by way of illustration only and thatthe invention is not necessarily limited thereto. For example, othermeans for heating the thermocouple, such as a torch or gas furnace, maybe provided. Accordingly, alternative embodiments of the apparatus andmodifications in the operating techniques will become apparent to thoseskilled in the art in view of my description and can be made withoutdeparting from the spirit of the described invention.

What I claim is:

1. An apparatus for evaluating the quenching power of a fluid whichcomprises the combination of a pyrometer means including a thermocouple,an elevated furnace means for heating said thermocouple, a samplecontainer below said furnace means, a vertically sliding holder forinitially supporting said thermocouple means within said furnace, atimer means, a switch means for initiating said timer, said switch meansbeing actuated by the free fall of said vertically sliding holder, andsaid timer being stopped in response to a predesignated temperaturesensed by said pyrometer means.

2. A compact portable quench oil tester comprising a thermocouple, apyrometer means including said thermocouple, an electrical heater forraising the temperature of the hot junction of said thermocouple, anelectric timer, a vertically slidable support for said thermocouple, aswitch means for initiating said electric timer, said switch means beingactuated by the free fall of said slidable support, and a second switchmeans controlled by said pyrometer and in turn stopping the electrictimer in re sponse to the thermocouple having cooled to a predesignatedtemperature.

3. A portable quenching oil tester comprising a frame means includingupstanding side wall members, a base, a top member, and a rear wall, apair of guide rails in alignment on opposite wall members, a hollowfurnace supported by said rear wall member, a sample container guidering on said base, a sliding member of the guillotine type supported insaid guide rails, a latch means pivotally fixed to said top member andadapted to secure said sliding holder at a high point on said frame, anda thermocouple means carried by said sliding member and dependingaxially of said frame means to be positioned alternately within saidfurnace and within a container on said container guide means.

4. An apparatus for evaluating the quenching properties of a quench oilwhich comprises in combination a pyrometer means including athermocouple assembly, a frame member, a cylindrical furnace supportedby said frame member at a point spaced above the base thereof, a slideof generally inverted U-shaped configuration supporting saidthermocouple assembly, a latch means for securing said slide in anelevated position on said frame whereby the bead of said thermocoupleassembly is disposed within said furnace, a sample container below saidfurnace and in axial alignment therewith whereby said thermocouple maydrop into said sample container, a con tainer guide means on the base ofsaid frame adapted to position said container below said furnace, anelectrical timer means, a micro-switch means carried by said frame andactuated by said slide for energizing said timer, and a relay meansoverriding said micro-switch on said timer, said pyrometer meanscontrolling said relay.

5. The apparatus of claim 4 wherein said pyrometer means includes a D.C. power supply and said microswitch means energizes said D. C. supply.

7 6; The apparatusof claim 2 wherein said electric timer has a largedisplay dial for-visually indicatingtheelapsed time.

7. Arr apparatus for demonstrating the relative quenching power ofvarious fluidswhich-comprisesin combinationa frame means, a pairofjguideraiis vertically extending within said frame means, a slidable'guill'otinetype holder 'between said railswithin said frame member, a

thermocouple me'anssnpportedby saidholder and'extending verticallydownward therefrom, a hollow electrical furnace within said frame member:and disposed intermcdiatethe 'top and .bottomthereo'f, a latch forsupporting said holder inan elevated positiontoplacethe hotjunction ofsaid thermocouple means in saidfurnace, a'sample container means belowsaidfu'rnace and in alignment with the central axis thereof, anelectric'timer means adapted 'toindicate the length of time necessary tocool the hot junction of thethermocouple'from a'first temperature to asecond temperature while immersed in a'testsarnple, a

first micro-switch actuated by said holder to initiate the timinginterval 'of said timer, a current indicator means connected to saidthermocouple, a second micro-switch actuated by said current indicatormeans to terminate the timing interval of said electricttimer when thethermocouple has cooled to the desired designated second tempcrature. I

'8. An apparatus "for use in evaluating the quenching properties of aquenching oiLsaid apparatus being of the type wherein a thermocouple isheated to a preselected temperature, the thermocouple is immersed in asample of the oil under test during which time cooling of thethermocouple occurs, and the time necessary for the thermocouple "tocool to. "a 'preselecte'd level isindicatcd,

means in the path of the free fall of said holdenwhereby thetherrnocouple isinitially supported within thehollow furnace'by'said-holder, and release of'the'latch permits the thermocouple ,tofall 'freely ithrough the furnace and into said sample containerandwhereby simultaneously atimer means is actuated 'by 'saidmicro-switch an'da current indicator means -associated with saidthermocouple, a second micro-switch'controlled by said indicator-means,said'secondmicro-switch being adapted 'to stop thesaid timer=meanswvhenthe thermocouplehas cooled to a preselected temperature. a

. References Citedtin thefile tof this-patent UNITED STATES PATENTSvBrace L. Oct. 27, 1925 V1',5S 8;828 2,475,138 l-Ioodilrvetal. July 5,1949 2,587,622 Jaife... Mar. 4, 1952 FOREIGN PATENTS I 903375 FranceJan. 8, 1945 v -kzue

1. AN APPARATUS FOR EVALUATING THE QUENCHING POWER OF A FLUID WHICHCOMPRISES THE COMBINATION OF A PYROMETER MEANS INCLUDING A THERMOCOUPLE,AN ELEVATED FURNACE MEANS FOR HEATING SAID THERMOCOUPLE A SAMPLECONTAINER BELOW SAID FURNACE MEANS, A VERTICALLY SLIDING HOLDER FORINITIALLY SUPPORTING SAID THERMOCOUPLE MEANS WITHIN SAID FURNACE, ATIMER MEANS, A SWITCH MEANS FOR INITIATING SAID TIMER, SAID SWITCH MEANSBEING ACTUATED BY THE FREE FALL OF SAID VERTICALLY SLIDING HOLDER, ANDSAID TIMER BEING